feat: add outdoor fair content fields

sql/migration_outdoor_fair_content.sql

@@ -0,0 +1,11 @@
+-- 户外招聘会内容字段：招聘会简介、招聘会整体流程
+-- 瀚高数据库 / PostgreSQL 兼容
+
+ALTER TABLE "cms_outdoor_fair"
+    ADD COLUMN IF NOT EXISTS "fair_introduction" TEXT;
+
+ALTER TABLE "cms_outdoor_fair"
+    ADD COLUMN IF NOT EXISTS "fair_process" TEXT;
+
+COMMENT ON COLUMN "cms_outdoor_fair"."fair_introduction" IS '招聘会简介';
+COMMENT ON COLUMN "cms_outdoor_fair"."fair_process" IS '招聘会整体流程';